THE DIFFERENCE OF SOUND IN ANECHOIC ROOM AND IN THE BERLIN PHILHARMONIC HALL
(Measurement of piano music 2)

Last time, a piece of a piano music was analyzed by the Sound Analyzer with
the integration time of 2.0 seconds. This time, the same sound will be analyzed
with the high time resolution (integration time of 0.01 s and calculation step
of 0.005 s). Also, it will be examined how the time history of the sound intensity is different between the anechoic room recording and the concert hall recording.

This is the running ACF measurement window of the piano motif recorded in
an anechoic room (same as last time).

Calculation conditions in SA. Now, the integration time is set as 0.01 sec and the
running step is set as 0.005 sec.

Integration time of 0.01 sec is the analysis method which raised the
resolution of the time-axis. This began from Analysis
of the Japanese voice 2. The graph of F(0) shows
the sound level averaged in 0.01 sec.

Anechoic room does not have reverberation. This is a greatly different world
with the actual world. Usually, a piano makes a beautiful sound by adding a reverberation of hall to
a sound of piano itself including strings and resonator. Since the sound of the
piano of anechoic room does not have a reverberation of a room, a cold sound of
piano is heard.

Leo Beranek explains in his book "How they sound concert and opera halls (pp
32-33)", about the decay of the instrumental sound in various acoustical
conditions.

Chart illustrating the interrelations among speed of music, reverberation time,
and ratio of loudness of early sound to that of reverberant sound, and the music
itself (tempos are identical). I is the decay of the instrumental sound and R is
the decay of the room sound.

Usually, the decay of the music consists of I (decay of the instrumental sound)
and R (decay of the room sound). But for the anechoic music analyzed here,
only I can be seen, because R is very small in the anechoic room.

A graph of F(0) is zoomed in around 0.2 s and 1.0
s. Attack and attenuation of a piano sound is measured.

The graph was further zoomed for one sound around 0.2 s.

When this piano music is performed in a hall, reverberation of the room is
added. It is thought that the attenuation of a sound pressure level is
changed.

To compare with anechoic room recording, a piano of concert hall recording is
analyzed. This is the Berlin philharmonic's recording of EDVARD GRIEG Piano
Concerto in A minor, op.16.

In the anechoic room recording, sound level has fallen by about 3 dB 0.005
seconds after a key is flipped. In contrast, in the Berlin recording shown in
the following figure, it has fallen only by 0.1dB. This is because the room
sound of the hall is added. Room sound consists of the initial reflective
sound and the late reverberation sound. As in the chart above, I (decay of
the instrumental sound) and R (decay of the room sound) can be clearly seen in
the graph below.

This is the analysis result of the Berlin recording. A first portion is a
symphony. The piano solo has started after 4 seconds.